I might be able to help a little with this as it sounds like you have the same issues I did.
Editing/creating a layout is pretty unresponsive for me too, had to just keep finding that sweet spot or entering numeric values over on the left.
As for loading a .ini, I assume you're trying to load an artpad of sorts? From what I can tell you can really only alter the defaults that are in that dropdown list (Float, Artist pad , Artist pad - medium, etc). So when you go to Settings > Artist Pad Mode there's a "Layout of artist pad" with a drop down menu, change it to whatever you'd modified. (Default, Medium, Small)
Of course, if you didn't modify any of the Artist Pad layouts, then I'm not actually too sure! I wouldn't mind getting a brief explanation of what's happening behind the scenes here because from a users perspective it seems rather unintuitive.
On the topic of reducing the size of the layouts background, I'm actually on this issue at the moment, but I believe the problem is the layout you're editing is a "docked" one that basically takes up a whole column of your screen. My next test when I get some time will be to alter one of the artist pad presets that appears to be floating in the preview.
Oh, and for things like holding Alt, Ctrl, yeah I noticed that too. It would work sort of fine with "Space"... bit of a delay compared to an actual keyboard, but it worked as intended in that I'd hold down space to pan around, and release it to turn back to my previous tool. But for some reason Alt required a toggle press, maybe such settings can be changed in the layout editor, I haven't had too much of a chance to get into it again today.